fix: add close and aclose methods to GeneratorWrapper

Currently, close and aclose methods are missing on GeneratorWrapper,
making it impossible to close generators from client code
without accessing the .generator directly, and missing span uploads in
the process.

This commit adds the missing methods for this usecase.

Author: yorickvP

langfuse/_client/observe.py

@@ -593,6 +593,17 @@ def __next__(self) -> Any:
 
             raise
 
+    def close(self) -> None:
+        output: Any = self.items
+
+        if self.transform_fn is not None:
+            output = self.transform_fn(self.items)
+        elif all(isinstance(item, str) for item in self.items):
+            output = "".join(self.items)
+
+        self.span.update(output=output).end()
+        self.generator.close()
+
 
 class _ContextPreservedAsyncGeneratorWrapper:
     """Async generator wrapper that ensures each iteration runs in preserved context."""
@@ -659,3 +670,14 @@ async def __anext__(self) -> Any:
             ).end()
 
             raise
+
+    async def aclose(self) -> None:
+        output: Any = self.items
+
+        if self.transform_fn is not None:
+            output = self.transform_fn(self.items)
+        elif all(isinstance(item, str) for item in self.items):
+            output = "".join(self.items)
+
+        self.span.update(output=output).end()
+        await self.generator.aclose()